Michelson interferometers are instruments used to obtain optical measurements. Interferometers have been incorporated into spectroscopic based systems that have proved to be effective in many types of chemical detection devices. For example, chemical detection devices used for detecting the presence of gasses in air use light spectrums to detect the presence or absence of various chemicals. A device might pass a sample of air through a filter that has a surface coating configured to trap or adhere to various chemical vapors. The trapped molecules are burned or vaporized to produce an electromagnetic spectrum, for example, a light spectrum. Analyzing the light spectrum produced allows the presence (or absence) of a chemical to be determined. The spectrometer is used to split the various wavelength components of the light spectrum and produce a pattern of lines which are indicative of the presence or absence of a chemical. Mass spectroscopic-based systems such as these are typically too large and require too much power to be portable.
Other types of chemical detection devices use quartz crystals as mechanical oscillators. The frequency of an oscillating quartz crystal is monitored to detect a change that would result from absorption of molecules of a particular chemical. The change in frequency is measured to detect the presence of the chemical. The change in mass, however, of quartz crystal oscillators as chemical vapors are absorbed can be very small, resulting in a change in the frequency of oscillation that is also very small. This limits the sensitivity of this type of quartz crystal-based detection device, which in turn reduces the number of applications that can reliably employ such a device.
There is a need for a sensing device that overcomes these shortcomings.